The need exists for low cost, rugged, long lived dose rate meters and dosimeters to satisfy military, civil defense, industrial, and individual civilian requirements. The applications include both monitoring for excessive exposure arising from emission of radioactive material by nuclear power and processing plants and monitoring doses and dose rates in order to support critical decisions in a nuclear war environment. Gamma ray measurement is of primary interest, but there also are requirements for measurement of other nuclear radiations.
Dosimeters measure total dose accumulated during the interval between successive readings. Most of the widely used available dosimeters are not user readable; they must be processed at a properly equipped laboratory. This procedure alone is adequate for situations in which the dose rate is unlikely to be high enough to cause excessive exposure during the reading interval, but this condition is unlikely to be satisfied in an emergency. If low dose rates cannot be guaranteed, dose rate measurement also is required. Geiger counters often are used for up to 0.1 or even one Roentgen.RTM. per hour, but ion chambers are the instrument of choice, providing high quality dose rate data at up to approximately 1000 R per hour.
The available dose rate meters are non-ideal for some applications. Geiger counters and ion chambers are electronic devices, typically weighing several pounds and occupying several hundred cubic inches. They are electronic devices, usually with battery life in the range of 50 to 500 hours. Battery shelf life limits may well preclude constructive use of many such instruments in any future emergency. Even the ruggedized versions of these instruments are shock sensitive, and their high cost limits the number likely to be available in an emergency.
Under severe radiation conditions, dosimeters are required in addition to dose rate meters, to guide both continued emergency utilization of personnel and their subsequent medical care. High range dosimeters exist, but most are not user readable.
It is clear that improved dose rate meters are needed and that improved dosimeters also might be useful for radiation protection under emergency conditions.